Ocular and systemic factors associated with diabetes mellitus in the adult population in rural and urban China. The Beijing Eye Study

Awareness and Knowledge of Glaucoma Among the Diabetic Population of Saudi Arabia: A Cross-Sectional Study

Introduction  Glaucoma, a leading cause of blindness, often progresses silently, leading to irreversible optic neuropathy. Diabetics are at higher risk of developing glaucoma. In Saudi Arabia, with a high prevalence of diabetes, limited research has focused on glaucoma awareness among diabetics. This study investigates the current status of glaucoma awareness and knowledge among the general and diabetic populations in Saudi Arabia. Methods A cross-sectional survey was conducted in March 2024 using a convenience sampling approach. An online questionnaire was distributed via social media and Google Forms, targeting Saudi Arabian residents, both diabetic and non-diabetic. The questionnaire, validated and translated into Arabic, included demographic questions and multiple-choice questions assessing glaucoma knowledge. A pilot study confirmed high internal consistency (Cronbach's alpha=0.840). The sample size was calculated to be 385 participants, ensuring a 95% confidence level and 5% margin of error. Results A total of 518 participants were surveyed, with 52.9% having diabetes. Most participants (74.3%) were unaware of the term "glaucoma," and only 11.8% had been diagnosed with the condition. Awareness was significantly higher among those who had undergone ocular examinations in the past year (64.7%). Knowledge levels varied, with 43.1% showing average knowledge, 30.3% weak knowledge, and 26.6% good knowledge. Significant associations were found between knowledge levels and factors such as diabetes status (p=0.0001), educational level (p=0.021), and sources of information, particularly medical staff (p=0.0001). Conclusion The study highlights a significant gap in glaucoma awareness and knowledge among the Saudi Arabian population, especially among diabetics. Increased educational efforts, particularly through medical staff, are crucial to improve glaucoma awareness and early detection, potentially reducing the burden of this disease. Further research should explore targeted interventions to enhance glaucoma knowledge among high-risk groups.

Dose-response association of metformin use and risk of age-related macular degeneration among patients with type 2 diabetes mellitus: a population-based study

Background: Recent studies have demonstrated that patients with type 2 diabetes mellitus (T2DM) who receive metformin have a decreased risk of developing age-related macular degeneration (AMD). However, other studies have also suggested that metformin may increase the risk of AMD development. Therefore, this study investigated the association between treatment with metformin and the risk of AMD in patients with T2DM by using Taiwan' National Health Insurance Research Database. Methods: Patients who received a diagnosis of new-onset T2DM between 2002 and 2013 were enrolled in this study. The patients were divided into patients treated and not treated with metformin to evaluate the risk of AMD after 5 years of follow-up. The logistic regression was used to estimate the risk of AMD associated with the intensity of treatment with metformin. Result: A total of 7 517 patients (103.16 patients per 10,000 people) developed AMD in 5 years after DM diagnosis. After adjusting for the relevant variables, patients with T2DM treated with <5 defined daily dose (DDD)/month of metformin had a lower risk of AMD (odds ratios [OR]: 0.93; 95% confidence interval [CI]: 0.88 0.99). Patients treated with >25 DDD/month of metformin had a higher risk of AMD (OR: 1.39; 95% CI: 1.08-1.78). Conclusion: Metformin use may be associated with a risk of AMD among patients with T2DM in a dose-dependent association manner, with the greater benefit at lower DDD/month. However, higher DDD/month exhibited an increased risk of AMD.

Association Between Glycemic Traits and Primary Open-Angle Glaucoma: A Mendelian Randomization Study in the Japanese Population

PURPOSE

A meta-analysis suggests a relationship between abnormal glucose metabolism and primary open-angle glaucoma (POAG); however, the causal association between them remains controversial. We therefore conducted a Mendelian randomization (MR) study to assess the causal association between genetically predicted glycemic traits and the risk of POAG.

DESIGN

Two-sample MR design.

METHODS

We examined the genetically predicted measures of fasting glucose, hemoglobin A1c (HbA1c), and fasting C-peptide, in relation to POAG. For the single nucleotide polymorphism (SNP)-exposure analyses, we meta-analyzed the study-level genome-wide associations of fasting glucose levels (n = 17,289; n of SNPs = 34), HbA1c (n = 52,802; n of SNPs = 43), and fasting C-peptide levels (n=1666; n of SNPs = 17) from the Japanese Consortium of Genetic Epidemiology studies. We used summary statistics from the BioBank Japan projects (n = 3980 POAG cases and 18,815 controls) for the SNP-outcome association.

RESULTS

We observed no association of genetically predicted HbA1c and fasting C-peptide with POAG. The MR inverse-variance-weighted (IVW) odds ratios (ORs) were 1.44 (95% confidence interval [CI], 0.78-2.65; P = .25) for HbA1c (per 1% increment) and 0.92 (95% CI, 0.56-1.53; P = .76) for fasting C-peptide (per 2-fold increment). A significant association between fasting glucose (per 10 mg/dL-increment) and POAG was observed according to the MR IVW analysis (OR = 1.48 [95% CI, 1.10-1.79, P = .009]); however, sensitivity analyses, including MR-Egger and weighted-median methods, did not support this association (P > .10).

CONCLUSIONS

We did not observe strong evidence to support the association between genetically predicted glycemic traits and POAG in the Japanese population.

Beta zone parapapillary atrophy in elderly Chinese

Purpose

Assess the beta zone parapapillary atrophy in elderly Chinese.

Patients and methods

The Beijing Eye Study 2011 is a population-based cross-sectional study, which includes 3468 patients with the average age of 64.5 ± 9.8 years. The beta zone of parapapillary atrophy was captured and analyzed morphometrically by using colour optic disc photographs.

Results

The beta zone was found in 1358 (39.9%) eyes, measuring 0.37 ± 0.84 mm2 in size, 203.5 ± 81.8° in circumferential angle, 0.36 ± 0.27 mm in the maximum radial extent, the most often and longest in the temporal peripapillary region, followed by the temporal inferior region and the temporal superior region, the nasal region at least. Beta zone has statistically significant association with male gender (P = 0.001), myopic refractive error (P = 0.003), thinner retinal nerve fiber layer thickness (P<0.001), thinner subfoveal choroidal thickness (P<0.001), bigger size of optic disc size (P<0.001). The size of beta zone has statistically significant association with longer axial length (P = 0.004)，increasing age (P<0.001), urban (P = 0.025), cardiovascular disease history (P = 0.025), with age related macular degeneration (P = 0.038), myopic ametropia (P<0.001), thinner retinal nerve fiber layer thickness (P = 0.001), thinner subfoveal choroidal thickness (P<0.001), bigger size of optic disc size (P = 0.001).

Conclusion

The population prevalence of beta zone was 39.9% in elderly Chinese. The area of the beta zone has statistically significant association with age, urban, the thickness of retinal nerve fiber layer, age related macular degeneration, cardiovascular disease history, axial length, myopic refractive error, size of optic disc size, the thickness of subfoveal choroid.

Optic disc morphology and peripapillary atrophic changes in diabetic children and adults without diabetic retinopathy or visual impairment

PURPOSE

To investigate the changes in optic disc morphology and peripapillary atrophy (PPA) in diabetic children and adults without diabetic retinopathy (DR) or visual impairment (VI).

METHODS

This cross-sectional study included two groups of subjects. One group included 91 children with type 1 diabetes mellitus (T1DM) and 86 healthy children, and the other group included 444 adults with T2DM and 442 healthy controls. The optic disc parameters including major and minor axis lengths, optic disc ovality (ODO), optic disc tilt, optic disc area and β-PPA area were analysed in all subjects. Optic disc rotation and the Bergmeister papilla were analysed only in children. Patients with diabetes and healthy controls were compared in each group of the study population.

RESULTS

In both groups, patients with diabetes and healthy controls were matched for age, sex and axial length (AL). Among the children, β-PPA area was significantly smaller in those with diabetes (0.29 ± 0.43 mm² ) than in the healthy controls (0.46 ± 0.58 mm² , p < 0.05). Multiple linear regression analysis showed that diagnosis of DM was negatively associated with β-PPA area. Longer AL and higher body mass index (BMI) were positively associated with β-PPA area. Among adults, ODO was significantly larger in those with diabetes (1.14 ± 0.09) than in healthy controls (1.12 ± 0.06, p < 0.05). Multiple linear regression analysis showed that the BMI and DM were potential risk factors affecting ODO.

CONCLUSION

Hyperglycaemia had different effects on the optic disc in children and adults. Unlike in healthy controls, hyperglycaemia had an impact on the peripapillary tissue in children and on optic disc shape in adults before DR and VI development.

Association Between Diabetes, Diabetic Retinopathy, and Glaucoma

PURPOSE OF REVIEW

The strength of the relationship between diabetes, diabetic retinopathy (DR), and glaucoma remains controversial. We review evidence supporting and refuting this association and explore mechanistic pathological and treatment relationships linking these diseases.

RECENT FINDINGS

While studies have shown diabetes/DR may increase the risk for glaucoma, this remains inconsistently demonstrated. Diabetes/DR may contribute toward glaucomatous optic neuropathy indirectly (either by increasing intraocular pressure or vasculopathy) or through direct damage to the optic nerve. However, certain elements of diabetes may slow glaucoma progression, and diabetic treatment may concurrently be beneficial in glaucoma management. Diabetes plays a significant role in poor outcomes after glaucoma surgery. While the relationship between diabetes/DR and glaucoma remains controversial, multiple mechanistic links connecting pathophysiology and management of diabetes, DR, and glaucoma have been made. However, a deeper understanding of the causes of disease association is needed.

Effect of Diabetes Control on Rates of Structural and Functional Loss in Patients with Glaucoma

PURPOSE

To investigate the association between levels of diabetes mellitus (DM) control and rates of visual field and retinal nerve fiber layer (RNFL) loss over time in glaucoma.

DESIGN

Retrospective cohort study.

PARTICIPANTS

A total of 351 eyes of 222 patients with type 2 DM with concomitant primary open-angle glaucoma (POAG) or suspected glaucoma extracted from the Duke Glaucoma Registry.

METHODS

All patients had at least 2 reliable standard automated perimetry (SAP) tests, 2 spectral domain OCT (SD-OCT) tests, and 2 glycated hemoglobin (HbA1c) measures over time with a minimum follow-up of 6 months. Values of HbA1c were summarized for each patient as mean, peak, and fluctuation across time. Multivariable linear mixed models were used to estimate the effect of HbA1c on rates of change in SAP mean deviation (MD) and OCT RNFL thickness loss over time while adjusting for various confounding factors.

MAIN OUTCOME MEASURES

Rates of change in MD and RNFL thickness over time.

RESULTS

Subjects had a mean baseline age of 62.5 ± 10.2 years and follow-up time of 6.9 ± 5.1 years. Subjects had an average of 4.8 SAP tests (range, 2-28), 3.6 SD-OCT tests (range, 2-10), and 8.3 HbA1c tests (range, 2-21). Average HbA1c mean was 7.1% ± 1.1% (range, 5.4-11.7), peak HbA1c over time was 8.1% ± 2% (range, 5.5-15.6), and HbA1c fluctuation was 0.6% ± 0.6% (range, 0-4.4). Mean rate of SAP MD change was -0.09 ± 0.20 decibel/year (median -0.06 decibel/year; interquartile range -0.15 to 0.01 decibel/year), and mean rate of RNFL change was -0.83 ± 0.51 μm/year (median -0.76 μm/year; interquartile range -1.06 to 0.56 μm/year). After adjustment for confounding factors, mean, peak, and fluctuation in HbA1c levels were not significantly associated with rates of MD change over time (P = 0.994, P = 0.689, P = 0.920, respectively), nor were rates of change in RNFL loss over time (P = 0.805, P = 0.575, P = 0.770).

CONCLUSIONS

We did not find a significant association between diabetes control, as measured by levels of HbA1c, and rates of visual field or RNFL loss over time in individuals with glaucoma or suspected glaucoma.

Spectrum of Eye Disease in Diabetes (SPEED) in India: A prospective facility-based study. Report # 4. Glaucoma in people with type 2 diabetes mellitus

Purpose

To estimate the proportion of people with type 2 diabetes mellitus (T2DM) and glaucoma in a facility-based cross-sectional observational study in India.

Methods

All people received a comprehensive eye examination. Glaucoma-specific examinations included applanation tonometry, optic disc and cup evaluation, and stereo biomicroscopy in all people; gonioscopy and visual field testing in glaucoma suspects. The International Society of Geographic and Epidemiologic Ophthalmology guidelines were used to diagnose and classify glaucoma.

Results

The study recruited 11,182 people (average age: 58.2 ± 10.6; range 39-96 years). Glaucoma was diagnosed in 4.9% (n = 547) people. About 76.8% (n = 420) of those with glaucoma had bilateral disease, and 98.7% (n = 540) were >40 years. Among people with bilateral disease, 94.5% (n = 397) had primary glaucoma - open angle in 59.3% (n = 228) and angle closure in 40.2% (n = 169). Diabetes duration was ≤10 years in 71.5% (n = 300) people. On linear regression, the following were associated with glaucoma: advancing age [compared with < 40 years age group; odds ratio [OR] in 50-60 year age group: 1.36 [95% confidence interval (CI): 1.01-1.8], P < 0.035); >60 years age group (OR: 2.05, 95% CI: 1.57-2.67; P < 0.001), and diabetic neuropathy (OR: 2.62, 95% CI: 1.35-5.10, P < 0.003). Glycemic control did not have significant association (P = 0.425).

Conclusion

Presence of glaucoma in people with T2DM in this cohort was similar to the general population prevalence studies in India. Glaucoma was invariably bilateral. A comprehensive eye examination in people age 40 years and older with diabetes and/or glaucoma is beneficial.

Diabetic Retinopathy Clinical Practice Guidelines: Customized for Iranian Population

PURPOSE

To customize clinical practice guidelines (CPGs) for management of diabetic retinopathy (DR) in the Iranian population.

METHODS

Three DR CPGs (The Royal College of Ophthalmologists 2013, American Academy of Ophthalmology [Preferred Practice Pattern 2012], and Australian Diabetes Society 2008) were selected from the literature using the AGREE tool. Clinical questions were designed and summarized into four tables by the customization team. The components of the clinical questions along with pertinent recommendations extracted from the above-mentioned CPGs; details of the supporting articles and their levels of evidence; clinical recommendations considering clinical benefits, cost and side effects; and revised recommendations based on customization capability (applicability, acceptability, external validity) were recorded in 4 tables, respectively. Customized recommendations were sent to the faculty members of all universities across the country to score the recommendations from 1 to 9.

RESULTS

Agreed recommendations were accepted as the final recommendations while the non-agreed ones were approved after revision. Eventually, 29 customized recommendations under three major categories consisting of screening, diagnosis and treatment of DR were developed along with their sources and levels of evidence.

CONCLUSION

This customized CPGs for management of DR can be used to standardize the referral pathway, diagnosis and treatment of patients with diabetic retinopathy.

Vascular Dysfunction in Diabetes and Glaucoma: A Complex Relationship Reviewed

Open-angle glaucoma (OAG) is a multifactorial disease characterized by progressive retinal ganglion cell death and visual field loss. Intraocular pressure, ocular perfusion pressure, and systemic vascular irregularities have all been identified as contributing factors for glaucoma onset and progression. Focal and systemic vascular abnormalities have also been well documented in diabetic patients. The relationship between diabetes mellitus and OAG remains enigmatic in the literature. As the pathogenesis of both diabetes mellitus and OAG involves compromised vascular regulation, this review was undertaken to further investigate their precise relationship. A literature review of published population-based studies was performed, with a focus on studies regarding blood flow abnormalities. Although current studies support the role of vascular contributions to both diseases, the association between glaucoma and diabetes yields contrasting results.

Association of Geroprotective Effects of Metformin and Risk of Open-Angle Glaucoma in Persons With Diabetes Mellitus

IMPORTANCE

Caloric restriction mimetic drugs have geroprotective effects that delay or reduce risks for a variety of age-associated systemic diseases, suggesting that such drugs might also have the potential to reduce risks of blinding ophthalmologic conditions for which age is a major risk factor.

OBJECTIVE

To determine whether the caloric restriction mimetic drug metformin hydrochloride is associated with reduced risk of open-angle glaucoma (OAG) in persons with diabetes mellitus.

DESIGN, SETTING, AND PATIENTS

Retrospective cohort study of patients aged 40 years or older with diabetes mellitus and no preexisting record of OAG in a large US managed care network from January 1, 2001, through December 31, 2010.

EXPOSURES

Quantity of metformin and other prescribed diabetes medications as captured from outpatient pharmacy records.

MAIN OUTCOMES AND MEASURES

Risk of developing OAG.

RESULTS

Of 150 016 patients with diabetes mellitus, 5893 (3.9%) developed OAG. After adjusting for confounding factors, those prescribed the highest quartile of metformin hydrochloride (>1110 g in 2 years) had a 25% reduced OAG risk relative to those who took no metformin (hazard ratio = 0.75; 95% CI, 0.59-0.95; P = .02). Every 1-g increase in metformin hydrochloride use was associated with a 0.16% reduction in OAG risk (adjusted hazard ratio = 0.99984; 95% CI, 0.99969-0.99999; P = .04), which predicts that taking a standard dose of 2 g of metformin hydrochloride per day for 2 years would result in a 20.8% reduction in risk of OAG. After accounting for potential confounders, including metformin and diabetic medications, the risk of developing OAG was increased by 8% (hazard ratio = 1.08; 95% CI, 1.03-1.13; P = .003) for each unit of increase in glycated hemoglobin level.

CONCLUSIONS AND RELEVANCE

Metformin use is associated with reduction in risk of developing OAG, and risk is reduced even when accounting for glycemic control in the form of glycated hemoglobin level. Other diabetes medications did not confer a similar OAG risk reduction. This study suggests that metformin may be affecting OAG risk on multiple levels, some involving improved glycemic control and some involving mechanisms outside glycemic control such as neurogenesis, inflammatory systems, or longevity pathways targeted by caloric restriction mimetic drugs. If confirmed by prospective clinical trials, these findings could lead to novel treatments for this sight-threatening disease.

Prevalence of Diabetic Retinopathy and Vision Loss in the Beijing Eye Study: the Potential Role of the Cerebrospinal Fluid Pressure

In the Beijing Eye Study, a population-based study carried out in 2001, 2006, and 2011, prevalence of diabetic retinopathy (DR) was 2.9 ± 0.3 % (95 % confidence interval 2.3, 3.5) per individual in 2011. Correspondingly, only 1.1 % of blindness and 0.8 % of visual impairment were caused by DR in East Asia. As in other populations, prevalence, severity, and 10-year incidence of DR were associated with higher levels of HbA1c, higher blood glucose concentration, longer known duration of diabetes, lower educational level, and higher blood pressure. Interestingly, the presence, severity, and 10-year incidence of DR were additionally correlated with higher estimated cerebrospinal fluid pressure and shorter ocular length. Higher cerebrospinal fluid pressure may lead to higher retinal vein pressure and subsequently higher retinal capillary blood pressure increasing fluid and blood extravasation. Shorter axial length or hyperopia may be associated with higher intraocular concentration of cytokines. Aging of the society, improvements in medical infrastructure, and lifestyle changes may profoundly increase prevalence of, and burden by, DR in China in the future.

Magnitude and determinants of glaucoma in type II diabetics: A hospital based cross-sectional study in Maharashtra, India

Background:

Glaucoma and diabetes have a common pathogenesis. We estimated the magnitude and determinants of glaucoma in adults with type II diabetes who presented to a tertiary level eye center in 2010.

Study Type:

A cross-sectional survey.

Methods:

Diabetes was diagnosed by history and measurement of blood sugar levels. Glaucoma was diagnosed by assessing optic disc morphology, visual fields, and intraocular pressure. Data were collected on patient demographics, clinical characteristics of diabetes and ocular status through interviews and measurements. The prevalence of glaucoma in diabetics was estimated, and variables were analyzed for an association to glaucoma. The 95% confidence intervals (CIs) were calculated. Statistical significance was indicated by P < 0.05.

Results:

The study cohort was comprised of 841 diabetics. The mean age of the cohort was 53.8 ± 10.7 years. There were 320 (38%) females. The prevalence of glaucoma was 15.6% (95% CI: 13.1-18.1). More than 75% of the diabetics had no evidence of diabetic retinopathy (DR). Half of the diabetics with glaucoma had primary open angle glaucoma. The presence of glaucoma was significantly associated to the duration of diabetes (Chi-square = 10.1, degree of freedom = 3, P = 0.001). The presence of DR was not significantly associated to the presence of glaucoma (odds ratio [OR] = 1.4 [95% CI: 0.88-1.2]). The duration of diabetes (adjusted OR = 1.03) was an independent predictor of glaucoma in at least one eye.

Conclusions:

More than one-sixth of diabetics in this study had glaucoma. Opportunistic screening for glaucoma during DR screening results in an acceptable yield of glaucoma cases.

Diabetes, glucose metabolism, and glaucoma: the 2005-2008 National Health and Nutrition Examination Survey

Background

Diabetes may affect vascular autoregulation of the retina and optic nerve and may be associated with an increased risk of glaucoma,but the association of prediabetes, insulin resistance, markers of glucose metabolismwith glaucoma has not beenevaluated in general population samples.

Objective

To examine the relation between diabetes, pre-diabetes, metabolic syndrome and its components and the levels of fasting glucose, HbA1c and HOMA-IR with the prevalence of glaucoma in the general U.S. population.

Methods

Cross-sectional study of 3,299 adult men and women from the 2005–2008 National Health and NutritionExamination Survey (NHANES). The presence of diabetes, prediabetes, the metabolic syndrome and its individual components and biomarkers of glucose metabolisms were based on standardized questionnaire and physical exam data and laboratory tests. The history of glaucoma was assessed through questionnaire during the home interview.

Results

Diabetes was strongly associated with prevalent glaucoma.In fully adjusted models, the odds ratiofor glaucoma comparing participants with diabetes with participants in the reference group with neither pre-diabetes nor diabetes was 2.12 (95% CI: 1.23, 3.67). The corresponding odd ratio comparing participants with pre-diabetes to those in the reference group was 1.01 (95% CI: 0.57, 1.82). Patients with 5 or more years of diabetes duration hadan OR for glaucoma of 3.90 (95% CI: 1.63, 9.32) compared with patients with <5 years of diabetes duration. We also found a hockey-stick shaped associations between biomarkers of glucose metabolisms and the prevalence of glaucoma.

Conclusions

Diabetes was associated with higher risk of glaucoma. Participants without diabetes but at the higher levels of fasting glucose, fasting insulin, HbA1c and HOMA-IR spectrum may also be at greater risk of glaucoma.

Diabetes mellitus and risk of age-related macular degeneration: a systematic review and meta-analysis

Age-related macular degeneration (AMD) is a major cause of severe vision loss in elderly people. Diabetes mellitus is a common endocrine disorder with serious consequences, and diabetic retinopathy (DR) is the main ophthalmic complication. DR and AMD are different diseases and we seek to explore the relationship between diabetes and AMD. MEDLINE, EMBASE, and the Cochrane Library were searched for potentially eligible studies. Studies based on longitudinal cohort, cross-sectional, and case-control associations, reporting evaluation data of diabetes as an independent factor for AMD were included. Reports of relative risks (RRs), hazard ratios (HRs), odds ratio (ORs), or evaluation data of diabetes as an independent factor for AMD were included. Review Manager and STATA were used for the meta-analysis. Twenty four articles involving 27 study populations were included for meta-analysis. In 7 cohort studies, diabetes was shown to be a risk factor for AMD (OR, 1.05; 95% CI, 1.00–1.14). Results of 9 cross-sectional studies revealed consistent association of diabetes with AMD (OR, 1.21; 95% CI, 1.00–1.45), especially for late AMD (OR, 1.48; 95% CI, 1.44–1.51). Similar association was also detected for AMD (OR, 1.29; 95% CI, 1.13–1.49) and late AMD (OR, 1.16; 95% CI, 1.11–1.21) in 11 case-control studies. The pooled ORs for risk of neovascular AMD (nAMD) were 1.10 (95% CI, 0.96–1.26), 1.48 (95% CI, 1.44–1.51), and 1.15 (95% CI, 1.11–1.21) from cohort, cross-sectional and case-control studies, respectively. No obvious divergence existed among different ethnic groups. Therefore, we find diabetes a risk factor for AMD, stronger for late AMD than earlier stages. However, most of the included studies only adjusted for age and sex; we thus cannot rule out confounding as a potential explanation for the association. More well-designed prospective cohort studies are still warranted to further examine the association.

The influence of retinal blood flow on open-angle glaucoma in patients with and without diabetes

PURPOSE

To evaluate the impact of retinal blood flow on optic nerve head (ONH) morphology in patients with open-angle glaucoma (OAG) with and without diabetes mellitus (DM).

METHODS

A total of 66 patients with OAG (14 with DM, 52 without DM) were assessed at baseline and 3-year follow-up for retinal capillary blood flow using confocal scanning laser Doppler and ocular structure using Heidelberg retinal tomography and optical coherence tomography.

RESULTS

Change in retinal tissue with zero blood flow in the superior and inferior retina was found to have a strong correlation with ONH changes in diabetic patients (r≥0.90, p≤0.03); however, no relation was found in the nondiabetic cohort. There were also significant changes in inferior mean flow that strongly correlated with changes in cup area (r = 0.97, p = 0.0029), cup/disc area ratio (r = 0.96, p = 0.0070), linear cup/disc ratio (r = 0.93, p = 0.0172), rim area (r = -0.97, p = 0.0036), and rim volume (r = -0.95, p = 0.0084) in diabetic patients only, while changes in the superior mean flow were only significantly associated with cup area (r = -0.30, p = 0.0498), cup volume (r = -0.36, p = 0.0178), and rim volume (r = 0.35, p = 0.0193) in nondiabetic patients.

CONCLUSIONS

In this cohort of patients with OAG, changes in retinal capillary blood flow correlated more strongly with changes in ONH morphology in patients with DM than in those without DM. These data suggest that changes in retinal blood flow may play a larger role in glaucomatous ONH progression in patients with OAG with DM.

Intraocular pressure and its relationship to ocular and systemic factors in a healthy Chinese rural population: the Handan Eye Study

PURPOSE

To describe the distribution of and factors related to intraocular pressure (IOP) in a healthy adult rural Chinese population in northern China.

METHODS

The Handan Eye Study is a cross-sectional, population-based study of eye diseases among 6,830 (90.4% response rate) rural Chinese persons aged 30+ years. Participants underwent an interviewer-administered questionnaire and a complete ocular examination, including standardized measurement of IOP with Perkins applanation tonometry.

RESULTS

After excluding persons with glaucoma, or those with diseases that have a marked effect on IOP or that preclude accurate IOP measurement, 6,101 persons were included in the current analysis. Mean IOP (mean ± standard deviation) of the study population was 15.0 ± 2.8 mmHg. Men had lower IOP than women (14.6 ± 2.8 mmHg versus 15.4 ± 2.7 mmHg, t = -8.37, P < 0.001). In the multivariate analysis younger age, female sex, presence of diabetes mellitus, higher blood pressure, higher body mass index, thicker central cornea and higher myopia were associated with higher IOP.

CONCLUSIONS

Mean IOP among persons living in rural northern China was similar to that recently reported in southern China. IOP appeared to be lower with increasing age in Chinese subjects, which contrasts with results in white populations.

Intraocular pressure and its determinants in subjects with type 2 diabetes mellitus in India

Objectives

This study was conducted to show the intraocular pressure (IOP) distribution and the factors affecting IOP in subjects with type 2 diabetes mellitus (DM) in India.

Methods

We measured the anthropometric and biochemical parameters for confirmed type 2 DM patients. A comprehensive ocular examination was performed for 1377 subjects aged > 40 years and residing in Chennai.

Results

A significant difference in IOP (mean ± standard deviation) was found between men and women (14.6±2.9 and 15.0±2.8 mmHg, p = 0.005). A significantly elevated IOP was observed among smokers, subjects with systemic hypertension and women with clinically significant macular edema (CSME). After a univariate analysis, factors associated significantly with higher IOP were elevated systolic blood pressure, elevated resting pulse rate and thicker central corneal thickness (CCT). In women, elevated glycosylated hemoglobin was associated with a higher IOP. After adjusting for all variables, the elevated resting pulse rate and CCT were found to be associated with a higher IOP.

Conclusions

Systemic hypertension, smoking, pulse rate and CCT were associated with elevated intraocular pressure in type 2 DM. Women with type 2 DM, especially those with CSME, were more prone to have an elevated IOP.

Do optic discs get "thinner" or "narrower?"

PURPOSE

To survey the literature to determine how the dimensions of the neuroretinal rim are commonly described, and to clarify and standardize the description of changes in the dimensions of the neuroretinal rim in glaucoma.

MATERIALS AND METHODS

Literature review of 275 articles describing the neuroretinal rim in glaucoma and a survey of ophthalmologists describing 2 disc photographs. Frequencies of descriptors of the neuroretinal rim were surveyed, which included "thinning" and "narrowing."

RESULTS

Of the 275 articles, 80 described the neuroretinal rim clinically. Forty-one articles used "thinning" to describe progressive loss of rim tissue in a radial axis, 13 articles used "narrowing" and rest used "width" to describe the characteristics of neuroretinal rim. Of the 295 ophthalmologists, 264 used "thinner," whereas 31 used "narrower" to describe the neuroretinal rim.

CONCLUSIONS

Accurate phenotyping is an essential part of patient care, research, and training. "Thinning" is currently used more commonly than "narrowing" in the literature to describe progressive loss of the neuroretinal rim in a radial axis. It would be appropriate to use "narrowing" for radial loss or decrease in width and "thinning" for decrease in the thickness of the rim.